1. Field of the Invention
The present invention relates to alkaline storage batteries, particularly, to the improvement of the construction of the plates used therein.
2. Description of Related Art
Since alkaline storage batteries are higher in energy density than lead acid batteries and, furthermore, can be sealed and have a long life, the field of utilization thereof has been increasingly expanded as electric sources of medium capacity for vehicles such as electromotive bicycles and electric cars in addition to portable devices such as mobile communication devices and small audio devices.
As the plates for alkaline storage batteries, there are sometimes used those which comprise a three-dimensional porous substrate such as a felt-like metal or a spongy metal on which an active material is supported, but mainly used are those which comprise a planar substrate such as a punching metal on which an active material is supported with a binder or on which an active material is coated and, then, sintered. This is because the punching metal substrates are inexpensive as compared with the three-dimensional porous substrates and, furthermore, various filling methods for the active material can be employed in the case of the punching metal substrates. Usually, the plates comprising a punching metal substrate are made by filling the substrate with an active material, then, subjecting it to a pressing, etc., and cutting it to a plate size. Thereafter, the plates are inserted in a container together with separators and the plates of opposite polarity, and the container is filled with an electrolyte and sealed to obtain a battery.